This book would be far more interesting without the manic pixie dream girl vibe. Seriously, the "romance" in this just blech. Maybe it's wrong to even call it romance. It's not like these people love each other. They're just attracted to each other and kind of stupidly obsessed while not actually being obsessed because they manage to focus on other concerns too. I blame adrenaline.
It's unfortunate because the whole poisoned water supply with demons plotline is interesting.